@Test
  public void testExisDay_blocks() {
    LocalDate testDay = LocalDate.of(2015, 9, 10);

    Cook p1 =
        createPerson("a", newHashSet(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY), newHashSet());
    Cook p2 =
        createPerson("b", newHashSet(MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY), newHashSet());
    p2.setExit(testDay.minusDays(1));

    CookingDay c1 = new CookingDay(p1, LocalDate.of(2015, 6, 30));

    kl = new CookingListImpl(Arrays.asList(p1, p2), Arrays.asList(c1));

    CookingDay day = kl.determineCookFor(testDay);

    assertThat(day.getCook(), is(p1));
  }
 private Cook createPerson(String id, HashSet<DayOfWeek> preferred, HashSet<DayOfWeek> noGo) {
   Cook person = new Cook(id);
   person.setNoGo(noGo);
   person.setPreferred(preferred);
   return person;
 }